Determination of Global Structure from Distance and Orientation Constraints in Biological Solids Using Solid-State NMR Spectroscopy

We report the results from a new solid-state NMR experiment, DANTE−REDOR, which can determine global secondary structure in uniformly (13C,15N)-enriched systems by simultaneously measuring distance and orientation constraints. Following a heteronuclear spin-pair selection using a DANTE pulse train, the magnitude and orientation of the internuclear dipole vector, within the chemical shift anisotropy (CSA) frame of the observed nucleus, are determined by tracking the dephasing of individual spinning sidebands under magic angle spinning. The efficacy of the experiment is demonstrated by measuring the imidazole side-chain orientation in U-[13C6,15N3]-l-histidine·HCl·H2O.